1. Field of the Invention
The present invention relates to a canal type earphone, and more particularly to a canal type earphone with a pressure equilibrium means, capable of eliminating a pressure difference between a user's external auditory meatus and an outside during wearing of the canal type earphone.
2. Description of the Related Art
A canal type earphone is a type of a speaker converting electric energy into acoustic energy, and enables listening by transferring vibration to an eardrum of an ear instead of emitting sound into a space.
The canal type earphone is put in a user's ear and enables speaker sound to be directly transferred into the user's ear. Since the canal type earphone enables listening to sound even at small output and rarely causes discomfort to those around a user in the course of listening, it is widely used for audio equipment such as a mobile phone and an MP3 player.
Earphones may be mainly classified into an open type earphone and a canal type earphone according to a method of wearing them on the ear. The open type earphone is adapted to wear the earphone as if to put it on an ear, and deteriorates sound insulation due to generation of a space therebetween since people have different ear shapes. On the other hand, the canal type earphone is adapted to insert the earphone into a user's ear, and uses earpieces (tips) having various sizes. Accordingly, the canal type earphone is wearable and has excellent sound insulation, compared to the open type earphone.
Although the canal type earphone is suitable to be used in a noisy place because of having excellent sound insulation, there is a problem in that a differential pressure may be generated due to a complete blockage between a user's external auditory meatus and an outside.
FIG. 1 shows an example of a conventional canal type earphone 1. As shown in the drawing, the canal type earphone includes a speaker unit 10, a housing 20 receiving the speaker unit 10, and an earpiece 23 installed on an outer surface of a cylindrical tube 25 which is integrally formed at the front of the housing 20.
The housing 20 defines a space for receiving the speaker unit 10, and is divided into a first housing 11a and a second housing 11b so as to easily mount the speaker unit 10. The tube 25 is integrally formed on a front surface of a first housing 11 so as to emit sound emitted from the speaker unit 10 into a user's ear. The tube 25 has a cylindrical shape and the earpiece 23 is fitted on an outer surface of the tube 25.
The earpiece 23 is made of a soft material such as silicon, and is formed of a shape and size corresponding to a user's external auditory meatus. The earpiece 23 is inserted into the user's external auditory meatus, thereby preventing sound emitted from the speaker unit 10 from leaking to the outside or preventing external noise from being transferred into the user's ear.
As shown in FIG. 2, when a user inserts the canal type earphone 1 into a user's external auditory meatus 2, the user's external auditory meatus 2 is completely blocked from the outside by the earpiece 23 installed to the canal type earphone 1. When the speaker unit 10 vibrates in a state in which air within the user's external auditory meatus may not be discharged to the outside, a pressure in the external auditory meatus is gradually increased so that a pressure difference is generated between the inside of the external auditory meatus and outdoor air.
As such, when a pressure difference is generated between the external auditory meatus and the outside, an eardrum 3 inside the external auditory meatus 2 is pressurized. For this reason, a user may not properly listen to sound emitted from the speaker unit 10, and a user's eardrum is also damaged in severe cases.
To solve these problems, the conventional canal type earphone has a vent groove g formed on an inside surface of the earpiece 23 coupled to the tube 25 or a vent hole h formed on the tube coupled with the earpiece, as shown in FIG. 1. Consequently, it may be possible to prevent generation of a differential pressure by discharging air within the external auditory meatus to the outside through the vent groove g or the vent hole h.
However, when the vent groove g is formed between the earpiece and the housing or the vent hole h is formed on the tube wrapped by the earpiece as in the related art, there is a problem in that the vent groove g or the vent hole h may be closed by the earpiece or the external auditory meatus when the earpiece is inserted into the external auditory meatus.
In addition, since the conventional vent groove g or the conventional vent hole h has a very short length for air passage and air within the tube is immediately discharged to the outside, there is a problem in that it is difficult to minutely adjust a discharge amount of air.    [Patent Document] Korean Patent Publication No. 10-0633050 (canal type earphone)